1. Field of the Invention
The present invention concerns a stacking device for automatic mail sorting machines.
2. Description of the Prior Art
An automatic mail sorting machine usually comprises the following parts:
a feed magazine in which an operator places mail to be sorted and which is then put in front of an unstacker, PA1 an unstacker whose function is to separate the letters so as to feed them one by one to a conveyor PA1 a read head associated with a microprocessor and facing the conveyor system to identify each letter and to assign it a storage area representative of its final destination, these storage areas being pigeonholes and/or stackers, PA1 a series of pigeonholes or stackers varying in number according to the machine and which serve as receptacles for the previously sorted letters. Each pigeonhole or stacker represents a specific sorting destination. PA1 reducing wasted time, PA1 eliminating unnecessary manipulation of the mail, PA1 reducing the number of operators, PA1 etc. PA1 restricted available space, implying a machine with small overall dimensions, PA1 machines for use by a single operator, with the aim of increasing cost-effectiveness by eliminating unnecessary manipulation of the mail, reducing the risk of incorrect manipulation, reducing wasted time and guaranteeing the quality of sorting by respecting the ordering of the mail items.
The present invention is more particularly concerned with the stacker which is so called because the letters are stored one against another to constitute a stack.
The widespread adoption of automatic mail processing has lead to the production of sorting machines for small sorting centers which carry out operations known as routing sorting and distribution sorting, which is the last stage of sorting before distribution to the addressees by the mailman.
Problems have been encountered with regard to the overall size of the machines and in response attempts have been made to optimize the number of sorting directions and consequently the number of stackers or pigeonholes in the machine. It has been found that routing sorting and distribution sorting can be carried out on a machine having less sorting receptacles than previously, provided that the number of sorting passes is increased.
The cost-effectiveness of the machines then depends on strict management of operation:
The greatest improvement in productivity can be obtained in distribution sorting, also known as delivery preparation. Delivery preparation means sorting and storing the mail in an order that must not thereafter be varied: the order of the mail items must correspond exactly to the mailman's route.
The number of successive sorting runs depends on the number of letters to sort, the sorting method adopted, the number of destinations, etc.
In addition to the problems of cost-effectiveness mentioned above, there is that of ensuring the quality of mail sorting, implying strict respect for the order of the letters throughout the sorting process.
One object of the present invention is to propose a sorting machine stacker for optimum stacking and transfer under the conditions currently prevailing in small sorting centers, namely: